Quick start

This document explains the basic steps of using the high-level API of TFHE-rs.

Setting up a Rust project

If you already know how to set up a Rust project, feel free to go directly to the next section.

First, install the Rust programming language tools. Visit https://rustup.rs/ and follow the instructions. For alternative installation methods, refer to the official Rust installation page.

After installing Rust, you can call the build and package manager Cargo:

$ cargo --version
cargo 1.81.0 (2dbb1af80 2024-08-20)

Your version may differ depending on when you installed Rust. To update your installation, invoke rustup update.

Now you can invoke Cargo and create a new default Rust project:

$ cargo new tfhe-example
    Creating binary (application) `tfhe-example` package
note: see more `Cargo.toml` keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

This will create a tfhe-example directory and populate it with the following:

$ tree tfhe-example/
tfhe-example/
├── Cargo.toml
└── src
    └── main.rs

1 directory, 2 files

You now have a minimal Rust project.

In the next section, we'll explain how to add TFHE-rs as a dependency to the project and start using it to perform FHE computations.

Using TFHE-rs and its APIs

To use TFHE-rs, you need to add it as a dependency to tfhe-example.

The Cargo.toml file is located at the root of the project. Initially, the file is minimal and doesn't contain any dependencies:

[package]
name = "tfhe-example"
version = "0.1.0"
edition = "2021"

[dependencies]

Then add the following configuration to include TFHE-rs:

tfhe = { version = "~1.0.1", features = ["integer"] }

Your updated Cargo.toml file should look like this:

[package]
name = "tfhe-example"
version = "0.1.0"
edition = "2021"

[dependencies]
tfhe = { version = "~1.0.1", features = ["integer"] }

If you are on a different platform please refer to the installation documentation for configuration options of other supported platforms.

Now that the project has TFHE-rs as a dependency here are the detailed steps to use its high-level API:

1. Import the TFHE-rs prelude with the following Rust code: use tfhe::prelude::*;

2. Client-side: configure and generate keys
3. Client-side: encrypt data
4. Server-side: set the server key
5. Server-side: compute over encrypted data
6. Client-side: decrypt data

This example demonstrates the basic workflow combining the client and server parts:

use tfhe::{ConfigBuilder, generate_keys, set_server_key, FheUint8};
use tfhe::prelude::*;

fn main() {
    let config = ConfigBuilder::default().build();

    // Client-side
    let (client_key, server_key) = generate_keys(config);

    let clear_a = 27u8;
    let clear_b = 128u8;

    let a = FheUint8::encrypt(clear_a, &client_key);
    let b = FheUint8::encrypt(clear_b, &client_key);

    //Server-side
    set_server_key(server_key);
    let result = a + b;

    //Client-side
    let decrypted_result: u8 = result.decrypt(&client_key);

    let clear_result = clear_a + clear_b;

    assert_eq!(decrypted_result, clear_result);
}

You can learn more about homomorphic types and associated compilation features in the configuration documentation.